CS268899B1 - A method of disposing of molybdenum waste liquor - Google Patents

Abstract

The waste molybdenum leachate is distilled at a temperature of 120 to 160 °C in a reboiler, alone, or with the addition of 1 to 30 vol. % concentrated sulfuric acid, to form nitric acid in a concentration of 55 to 60 wt. % and a distillation residue consisting of molybdenum oxides, mainly molybdenum oxides, and concentrated sulfuric acid, and this distillation residue is filtered under reduced or increased pressure, preferably at a temperature of 30 to 90 °C, whereby molybdenum oxides are obtained on the filter and the filtrate contains concentrated sulfuric acid, and both acids thus isolated can be used again for molybdenum etching.

Description

Author of the invention Sabbath Stanislav ing., Prague, VOSTATEK FRANTIŠEK, LENEŠICE (54) Waste molybdenum leachate disposal method (57) Waste molybdenum leachate is distilled at a temperature of 120 to 160 ° C in the digester itself, optionally with the addition of 1 to 30 vol% % concentrated sulfuric acid to form nitric acid at a concentration of 55 to 60 wt. and a distillation residue consisting of molybdenum oxides, predominantly molybdenum oxides and concentrated sulfuric acid, and the distillation residue is filtered under reduced or elevated pressure, preferably at a temperature of 30 to 90 ° C, to obtain molybdenum oxides on the filter and the filtrate contains concentrated sulfuric acid and the two isolated acids can be used again for etching molybdenum.

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CS 268899 Bl

The invention relates to a process for the disposal of molybdenum waste liquors after etching of tungsten fibers while recovering the starting materials.

It is known that tungsten filaments are wound on molybdenum wire in the production of incandescent lamps and this is etched off with a mixture of nitric acid, sulfuric acid and water. The leachate obtained is treated to a small extent as an additive in the production of nitrogen fertilizers, but most of the leachate accumulates in the landfill.

The process of treating molybdenum waste liquors according to the invention eliminates the problems of disposal and allows the re-use of the starting materials. The waste liquors according to the invention are treated by distillation, in which, after distillation of nitric acid at a concentration of 55 to 60%, molybdenum oxides from the concentrated sulfuric acid precipitate. Subsequent filtration yields concentrated sulfuric acid and, after washing with water, molybdenum oxides.

Accordingly, it is an object of the present invention to provide a process for the disposal of molybdenum waste liquor, e.g. from the manufacture of incandescent filaments, and a simultaneous regeneration of feedstocks, wherein the molybdenum waste liquor is distilled at 120-160 ° C in the reboiler alone, optionally with 1 to 30 vol. % concentrated sulfuric acid to form nitric acid at a concentration of 55 to 60 wt. and a distillation residue consisting of molybdenum oxides, predominantly molybdenum oxide and concentrated sulfuric acid, and the distillation residue is filtered under reduced or elevated pressure, preferably at a temperature of 30 to 90 ° C, whereby molybdenum oxides are obtained on the filter and the filtrate can be reused preparation etching mixture i.

Example 1

1600 ml of molybdenum waste liquor was charged to the reaction vessel and 59% nitric acid (900 ml) was isolated by distillation. The precipitated molybdenum oxides from the 430 ml concentrated sulfuric acid rain residue were filtered off, washed with water and dried. The obtained mixture of nitric acid and sulfuric acid was again used for etching molybdenum.

Example 2

The reaction vessel was charged with 1300 ml of molybdenum waste liquor and 200 ml of concentrated sulfuric acid. 700 ml of 60% nitric acid was distilled off and molybdenum oxides were filtered from the distillation residue containing 550 ml of concentrated sulfuric acid, washed with water and dried. The mixture of nitric acid and sulfuric acid was again used to etch molybdenum wire.

Claims (1)

REFLECT THE INVENTION Method for the disposal of molybdenum waste liquors, for example from the manufacture of filaments for incandescent lamps, while recovering the starting materials, characterized in that the molybdenum waste liquor is distilled at 120 to 160 ° C in the digester itself, optionally with the addition of 1 to 30 vol% % concentrated sulfuric acid to form nitric acid at a concentration of 55 to 60 wt. and a distillation residue consisting of molybdenum oxides, predominantly molybdenum oxides and concentrated sulfuric acid, and the distillation residue is filtered under reduced or elevated pressure, preferably at a temperature of 30 to 90 ° C to obtain molybdenum oxides on the filter and the filtrate contains concentrated sulfuric acid .